<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            display: flex;
        }

        div {
            display: flex;
            height: 400px;
            width: 500px;
            flex-wrap: wrap;
            /* 从头部开始排列 */
            /* align-content: flex-start; */
            /* 从尾部开始排列 */
            /* align-content: flex-end; */
            /* 在侧轴中间显示 */
            /* align-content: center; */
            /* 子元素平分侧轴 */
            /* align-content: space-around; */
            /* 先子项分布在侧轴两头 再平分侧轴剩余空间 */
            /* align-content: space-between; */
            /* 子项元素平分父元素高度 */
            align-content: stretch;
            background-color: pink;
        }

        div span {
            /* height: 50px; */
            width: 100px;
            background-color: purple;
        }
    </style>
</head>

<body>
    <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
        <span>4</span>
        <span>5</span>
        <span>6</span>
        <span>7</span>
        <span>8</span>
        <span>9</span>
        <span>10</span>
        <span>11</span>
        <span>12</span>
        <span>13</span>
        <span>14</span>
        <span>15</span>
    </div>
</body>

</html>